The UCI DMA & Protein MicroArray Facility was initially established in 1999 as a Comprehensive Cancer Center Shared Resource Core Facility, directed at assisting both North and South Campus investigators performing microarray expression analysis. About 200 investigators inside and outside the South Campus have been provided services in the last five year period. We primarily utilize the Affymetrix GeneChip array system to monitor gene expression and perform SNP/genotype mapping. Our mission is to provide RNA expression and genomic DMA analysis in a consistent and timely manner that is of the highest quality for all of our Facility's users. In addition to providing experimental expertise for performing gene expression and SNP/genotype mapping protocols, the staff provides advice and consultation on experimental design, and data analysis approaches and statistics for microarray based research. Currently, the primary use of this technology is to determine the differential expression patterns of genes, either within cells or tissues. This technology enables investigators to compare patterns of expression in diseased and normal cells, cancer cells and non-cancerous cells and in different tissue types. The goal of these types of studies is to better understand the processes that potentially lead to diseased states and to find new or better ways of either controlling or stopping the progression of diseased states. A rapidly increasing use of this technology is analysis of genotypic variants (SNPs) to map disease-causing genes. These types of approaches will provide insight into multifactorial disease states. Genomewide information unlike individual gene information can be used to understand the more subtle patterns of diseases caused by multiple genes or by the confluence of environmental and genetic factors. Because of the great amount of detailed information provided from genomewide arrays, it is likely that microarrays will become an even more important tool not only in understanding disease processes, but also in disease diagnosis and the design of individualized therapies.